In a receiver of a communications system the received signal must be demodulated to extract the transmitted data bits from the received radio signal.
In a system using quadrature amplitude modulation (QAM) the receiver will typically process the received signal in a block-wise fashion using a common QAM detection threshold for a block of equalised data symbols.
The present inventors have ascertained that in certain circumstances this scheme yields sub-optimal performance. For example, if the equalised data symbols carry the signal strength information which can be used to improve channel decoding performance, use of a common QAM threshold will not yield good performance due to the amplitude fluctuation of equalised data symbols.